/*  Sesame - Storage and Querying architecture for RDF and RDF Schema
 *  Copyright (C) 2001-2006 Aduna
 *
 *  Contact: 
 *  	Aduna
 *  	Prinses Julianaplein 14 b
 *  	3817 CS Amersfoort
 *  	The Netherlands
 *  	tel. +33 (0)33 465 99 87
 *  	fax. +33 (0)33 465 99 87
 *
 *  	http://aduna-software.com/
 *  	http://www.openrdf.org/
 *  
 *  This library is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU Lesser General Public
 *  License as published by the Free Software Foundation; either
 *  version 2.1 of the License, or (at your option) any later version.
 *
 *  This library is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 *  Lesser General Public License for more details.
 *
 *  You should have received a copy of the GNU Lesser General Public
 *  License along with this library; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */
package com.openess.bigsearch.engine.BTree.other;

/**
 * Class providing utility methods for handling byte arrays.
 **/
public class ByteArrayUtil {
	/**
	 * Puts the entire <tt>source</tt> array in the <tt>target</tt> array at
	 * offset <tt>offset</tt>.
	 **/
	public static void put(byte[] source, byte[] target, int offset) {
		System.arraycopy(source, 0, target, offset, source.length);
	}

	/**
	 * Gets the subarray from <tt>array</tt> that starts at <tt>offset</tt>.
	 **/
	public static byte[] get(byte[] array, int offset) {
		return get(array, offset, array.length - offset);
	}

	/**
	 * Gets the subarray of length <tt>length</tt> from <tt>array</tt> that
	 * starts at <tt>offset</tt>.
	 **/
	public static byte[] get(byte[] array, int offset, int length) {
		byte[] result = new byte[length];
		System.arraycopy(array, offset, result, 0, length);
		return result;
	}

	public static void putInt(int value, byte[] array, int offset) {
		array[offset] = (byte) (0xff & (value >> 24));
		array[offset + 1] = (byte) (0xff & (value >> 16));
		array[offset + 2] = (byte) (0xff & (value >> 8));
		array[offset + 3] = (byte) (0xff & value);
	}

	/**
	 * @param array
	 * @param offset
	 * @return
	 */
	public static int getInt(byte[] array, int offset) {
		return ((array[offset] & 0xff) << 24)
				| ((array[offset + 1] & 0xff) << 16)
				| ((array[offset + 2] & 0xff) << 8)
				| (array[offset + 3] & 0xff);
	}

	public static void putLong(long value, byte[] array, int offset) {
		array[offset] = (byte) (0xff & (value >> 56));
		array[offset + 1] = (byte) (0xff & (value >> 48));
		array[offset + 2] = (byte) (0xff & (value >> 40));
		array[offset + 3] = (byte) (0xff & (value >> 32));
		array[offset + 4] = (byte) (0xff & (value >> 24));
		array[offset + 5] = (byte) (0xff & (value >> 16));
		array[offset + 6] = (byte) (0xff & (value >> 8));
		array[offset + 7] = (byte) (0xff & value);
	}

	public static long getLong(byte[] array, int offset) {
		return ((long) (array[offset] & 0xff) << 56)
				| ((long) (array[offset + 1] & 0xff) << 48)
				| ((long) (array[offset + 2] & 0xff) << 40)
				| ((long) (array[offset + 3] & 0xff) << 32)
				| ((long) (array[offset + 4] & 0xff) << 24)
				| ((long) (array[offset + 5] & 0xff) << 16)
				| ((long) (array[offset + 6] & 0xff) << 8)
				| ((long) (array[offset + 7] & 0xff));
	}

	/**
	 * Checks whether <tt>value</tt> matches <tt>pattern</tt> after
	 * <tt>mask</tt> has bee applied to <tt>value</tt>. In other words: this
	 * method returns true if <tt>value[i]&amp;mask[i] == pattern[i]</tt> for
	 * all i.
	 **/
	public static boolean matchesPattern(byte[] value, byte[] mask,
			byte[] pattern) {
		for (int i = 0; i < value.length; i++) {
			if ((value[i] & mask[i]) != pattern[i]) {
				return false;
			}
		}
		return true;
	}

	/**
	 * Checks whether <tt>subValue</tt> matches the region in
	 * <tt>superValue</tt> starting at offset <tt>offset</tt>.
	 **/
	public static boolean regionMatches(byte[] subValue, byte[] superValue,
			int offset) {
		for (int i = 0; i < subValue.length; i++) {
			if (subValue[i] != superValue[i + offset]) {
				return false;
			}
		}
		return true;
	}

	/**
	 * Compares two regions of bytes, indicating whether one is larger than the
	 * other.
	 * 
	 * @param array1
	 *            The first byte array.
	 * @param startIdx1
	 *            The start of the region in the first array.
	 * @param array2
	 *            The second byte array.
	 * @param startIdx2
	 *            The start of the region in the second array.
	 * @param length
	 *            The length of the region that should be compared.
	 * @return A negative number when the first region is smaller than the
	 *         second, a positive number when the first region is larger than
	 *         the second, or 0 if the regions are equal.
	 */
	public static int compareRegion(byte[] array1, int startIdx1,
			byte[] array2, int startIdx2, int length) {
		int result = 0;
		for (int i = 0; result == 0 && i < length; i++) {
			result = (array1[startIdx1 + i] & 0xff)
					- (array2[startIdx2 + i] & 0xff);
		}
		return result;
	}

	/**
	 * Returns the hexadecimal value of the supplied byte array. The resulting
	 * string always uses two hexadecimals per byte. As a result, the length of
	 * the resulting string is guaranteed to be twice the length of the supplied
	 * byte array.
	 **/
	public static String toHexString(byte[] array) {
		StringBuffer result = new StringBuffer(2 * array.length);
		for (int i = 0; i < array.length; i++) {
			String hex = Integer.toHexString(array[i] & 0xff);
			if (hex.length() == 1) {
				result.append('0');
			}
			result.append(hex);
		}
		return result.toString();
	}
}